This invention relates generally to modular flat panel display devices and particularly to a waveform generator for generating a triangular scanning waveform in such devices.
A modular flat panel display device in which the instant invention can be utilized is described in U.S. Pat. No. 4,117,368 issued to F. J. Marlowe, et. al. The Marlowe device consists of an evacuated envelope which is divided into channels by a plurality of vanes. Each of the channels include guide meshes for propagating electron beams along the lengths of the channels. When a particular line of the visual display is to be produced, the electron beams are ejected from the guide meshes and travel toward the display screen. The vanes support deflection electrodes which are biased with varying deflection potentials. These deflections potentials cause the electrons traveling from the guide meshes to the display screen to be scanned transversely across the channels. The electron beams of all the channels are simultaneously ejected from between the guide meshes so that a portion of the same horizontal line of the visual display is simultaneously generated across each of the channels. In order to avoid charging the capacitor formed by the deflection electrodes on opposite sides of a vane, the same deflection voltage is applied to both deflection electrodes. Adjacent channels, therefore, are scanned in opposite directions. Video information, therefore, must also be supplied to adjacent channels in reverse order.
A system which reverses the order of data supplied to adjacent channels of a modular display device is described in U.S. Pat. No. 4,080,630 issued to F. J. Marlowe. In the Marlowe system, the incoming video data are in analog form and are digitized in an analog-to-digital (A/D) converter. The digitized output of the A/D converter is supplied to a reversing register which includes two shift registers. The two shift registers are coupled through switching means to a primary shift register so that either of the shift registers can load the primary shift register. When the switching means is coupled to one of the registers, the data are read out of the primary register in the same order as received. When the switching means are coupled to the other shift register, the data are read out of the primary register in an order reversed from the received order.
U.S. Pat. No. 4,257,068 issued to L. B. Johnston also shows a system which reverses the order of data supplied to adjacent channels of a modular display device. The Johnston system replaces the two shift registers of Marlowe with a left/right shift register.
The instant invention is directed to a triangular waveform generator which can be used to scan the channels of the device described in U.S. Pat. No. 4,117,368 and which can be used in conjunction with the devices described in U.S. Pat. Nos. 4,080,630 and 4,257,068.